Apparatus for spectrophotometric quantitative analysis



y 31, 1951 T. E. WEICHSELBAUM 2,562,874

APPARATUS FOR SPECTRO-PHOTOMETRIC QUANTITATIVE ANALYSIS Filed Feb. 17, 1950 a /f Help A l2 3 I/ FIG. 3.

INVENTOR. THEODORE E. WEICHSELBAUM AT TORNEY Patented July 31, 1951 APPARATUS FOR SPECTROPHOTOMETRIC QUANTITATIVE ANALYSIS Theodore E. Weichselbaum, Normand nMou assignor to Applied Research Corporation, a corporation of Missouri Application February 17, 1950, SerialNo 144,693

This invention relates in general to apparatus for speotro-photometric quantitative analysis and, more particularly, to a new and novel spectro-photometric flame injection burner of the type generally disclosed in my co-pending application, Serial No. 55,754jfiled October 21, 1948, now Patent No. 2,532,687.

It is the primary object of'the present invention to provide a flame injection burner for spectro-photometric quantitative analysis which is simple, accurate, precise, and is particularly adapted to employ acetylene and similar gas as a fuel. It is a further object of the present invention to provide a simplefi'highly efficient spectro photometric flame producing'apparat'us or burn er which is capable of accurate, reliable; and uni-' form operation.

It is also an object of the present invention to provide a photometric burner having injection flame controlling meanswhich can bereadily ad'- juste'd to produce a steady'uniform flame inan accurately controlled manner so as to produce a photometrically measurable flame-effect which bears a precise quantitative relation to the chemical c'onstituency'of the solution being injected thereinto. p

It is an additional object of the present invention to provide apparatus of the type stated which is economical in construction and simple in operation;

'With the above and'o'ther objects'in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts presentlyfdescribed and pointed out inthe claims. i I

In the accompanying drawing- Figure'i is" a top plan view of a photometric burner constructed in accordance with and embodying the present'invehtion;

' Figure 2is'a vertical sectionahview of the photometric burnentakem along line. 2-'-2 of Figure 1; and w Figure 3 is a fragmentary vertical sectional view'of a modified form of photometric burner constructed in accordance 'with and-embodying the present invention.

Broadly speaking, the present invention resides in the use of a color-analyzing photometer in cornbination"with'an oxy-acetylene burner or so-called lamp having means for-introducing a precisely constant flowof the liquid or solution to ice-analyzed directly into the'interior portion oftheflame. 1 Referring now in more" detail and by refer 60laims. (G1. I 23-253) ence characters tothe drawing, which illustrate a preferred embodiment of the present invention, A designates a spectro-photometric quantitative analysisburner' comprising a cylindrical shell I provided'in its lower end with a transverse closurediskZ peripherally Welded or brazed thereto to form a gas-tight permanent seal. Brazed or otherwise secured within, and extending radially outwardly from, the-:shell I is a gas-inlet tube 3 adapted 'for connection by aconventional rubber hose or other similarmeans (not shown) to" a source of acetylene or other suitable fuel gas. Between the gas-inlet tube 3 and its upper open end 4,- the shell I is provided with an external taper, so that its'external diametral sizeadja cent such upper end! is several thousandths smaller than its external diametral." size just above the gas-inlet tube 3. Slip-fitted on, and

extending "down over, the shell I and having a complementary internal' taper is an outer sheil 5 provided atits upper endwith atop wall 6 having a-relatively largewconcentric aperture I.

Projecting at :its lower end through and being brazed into theclosure dislt 2 and-extending axially upwardlythrough the shell I is a nozzle tube B-havingan integrallower end wall 9 and forminga gas chamber-I0 within the shell I. At its upperend, .thettubeB terminates just below-the aperture 1 in the provision of "anannular gasoutlet orifices and in such upper-end is threadedly provided with a nozzle II having a frustoconical upper face l2 and-a central or axial bore I3 which flares; out at its upper and lower end, as at I4 and I5. Welded in the upper end, of the nozzle-tube-8,--in downwardly spaced relationto the nozzle I I,-is a-collar I6 having anannular series of apertures I! and a central bore 18. Brazed linto andextending radially outwardly from the 'lower-projecting-end of, the nozzle tube 8 is a tubular lateral off-take I9 for connection to a conventional oxygen line (not shown). Similarly-welded at its-lower endin the nozzletube end-wall 94s afine-boreliquid-tube or cape illary v2|) which extends axially therethrough and projects downwardly at its lower end for a substantial distance so as to dip down into ,the liquid sample held withina conventional beaker. (notshownh Adjacent its upper end, the capillary Z0 extends-through and is snugly held in the collar-I6 and, at "its upper end, the capillary 20 extends through and is of substantally smaller diameterthan the bore I3 of the nozzle II so as to provide an annularv space' therebetween and thus createa Venturieffect at the mouthof the nozzle II. It should be noted in this con nection that the upper end of the capillary 20 i should preferably be precisely concentric with the bore It to insure maximum uniformity and accuracy of analytical results.

The outer shell 5 may be adjusted vertically up or down as a result of interfitting friction of the complementary tapers, so that its upper or orifice end will be located at an optimum position in relation to the upper or discharge end of the nozzle tube 8, since it has been found that this orifice adjustment is somewhat critical for gases, such as acetylene and the like. Once set, changes are only necessary at infrequent intervals or when the quality of the fuel gas changes substantially.

In use, the burner A is set in operation by first turning on the acetylene supply and the gas fills the chamber ll! exiting through the annular space s between the aperture 1 and the upper end of the nozzle tube 8. The burner A may then be lit by applying a match or other conventional pyrophoric means to the stream of gas issuin therefrom. The oxygen is then turned on and the gas pressures are adjusted by conventional pressure regulators (not shown) until the gases burn steadily and evenly in a light blue practically colorless flame. Under these conditions, the flame will burn straight up, so to speak, in the form of a vertical cylinder.

The stream of oxygen will flow upwardly through the nozzle tube 8 and issue in a highpressure blast through the constricted orifice formed between the nozzle-bore l3 and the upper end of the capillary 20, causing the flame to taper down to an intensely hot conical blast and also creating a Venturi effect directly upon the capillary 2B. Thereupon, a suitable quantity of the liquid sample is placed in a carefully cleaned beaker (not shown) andthe latter set up under the lower or intake end of the capillary 20, so that such intake end of the capillary 20 will dip down into the liquid. The suction capillary 20 draws the liquid sample upwardly in a constant flow. As the liquid leaves the upper end of the capillary 20, it is immediately atomized or volatilized and projected into the interior of the flame for immediate ionization. It should be noted that the volatilization and ionization of the solution are practically simultaneous.

As the sample is ionized in the flame, a characteristic color will be imparted thereto, such as yellow for sodium, red for lithium, and so on. Furthermore, the degree of intensity of coloration is directly proportional to the percentage of such cation in the sample. This degree of color intensity can be analytically measured as more fully described in my co-pending application, Serial No. 55,754. During analytical procedure, the pressures of entering gases should be held constant within very close limits. t I

If desired, I may also provide a'modified form of flame burner A, which is substantially identical with the previously described flame burner A except that it is provided with a shell I of uniform outer diametral size having an enlarged threaded section 21 of rather coarse pitch for engagement with a complementarily threaded section 22 on the interior face of an outer shell 5'. It should be noted in this connection that, above the threaded sections 2|, 22, the shells I, 5','fit rather snugly, so that no appreciable amount of air will be drawn into the flame. Thus, by turning the shell 5 with respect to the shell I a vertical adjustment of the orifice may be obtained.

With apparatus of the present invention, variations in ambient temperatures and atmospheric conditions have no adverse effect upon the analytical results. The burner of the present invention furthermore obviates all side efiect due to condensation of volatilized liquid, inasumch as a constant amount of liquid per unit of time is delivered directly into the flame.

It should be understood that changes and modifications in the form, construction, arrangement and combination of the several parts of the apparatus for spectro-photometric quantitative analysis may be made and substituted for those herein shown and described without departing from the nature and principle of the present invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a spectro-photometric analytical apparatus, a flame generating burner comprising an elongated cylindrical shell chamber having an inlet tube adjacent one end for introducing a combustible gas into the chamber, said cylindrical shell chamber being provided at its other end with a diametrically reduced substantially circular aperture, a nozzle-tube of substantially smaller diameter extending through said cylindrical shell chamber and having at one end a discharge nozzle adjacent to and substantially concentrically within and spaced from the substantially circular aperture producing an annular flame port therewith and being provided with a portion having a constricted passage opening adapted to create therewith a Venturi eifect, said nozzle-tube being provided adjacent its other end with an inlet tube for receiving a high-pres sure combustion-supporting gas, and a liquidsample intake tube of smaller diameter disposed within and extending coaxially through the nozzle-tube, said liquid-sample intake tube terminating at one end substantially concentrically within the constricted passage opening and at its other end projecting outwardly from the burner for insertion into a body of liquid to be analyzed.

2. In a spectro-photometric analytical apparatus, a flame generating burner comprising an elongated cylindrical shell chamber having an inlet tube adjacent one end for introducing a combustible gas into the chamber, said cylindrical shell chamber being provided at its other end with a diametrically reduced substantially circular aperture, a nozzle-tube of substantially smaller diameter extending through said cylin drical shell chamber and having at one end a discharge nozzle adjacent to and substantially concentrically within and spaced from the substantially circular aperture providing an annular flame port therewith and being provided with a portion having a constricted passage opening adapted to create therewith a Venturi effect, said nozzle-tube being provided adjacentits other end with an inlet tube for receiving a high-pressure combustion-supporting gas, and a substantially straight liquid-sample intake tube of smaller diameter disposed within and extending coaxially through the nozzle-tube, said liquid-sample intake tube terminating at one end substantially concentrically within the constricted passage opening and at its other end projecting outwardly from theburner for insertion into a body of substantially circular aperture} a gas inletmeans it mng 7 into "the interior" of the first tubular 'J'ne nber" adjacent-the closed? end thereof for i'int roducing a' combustible gas fthereinto; a seclOIid tubular member disposed within, and being jot. substantially 'smaller diametral sizejthan the Ifilrsjt tubular member and being closed atgone end adjacent'to the closed end of the firsttubular member and terminating at its other end in concentrica'elation to the aperture for providingin ,cooperation ,therewith an. annular fiamaoriflce, aniinlettube opening into the second tubeadjacent theclosed end thereof for introducing thereinto a flame supporting gas anda substantially straight.liquid-sample'intake tube extending coaxiallythrough the second-tubularimember, said liquid-sample intake tube being of substantially papillary dimensions and terminating atone: end adjacent to the annular flameorificeproviding a discharge opening, said liquid-sample intake tube projecting outwardly from the closed end of the second tubular member for insertion into a body of liquid to be analyzed, said second tubular member further being provided at its other end with means having a constricted passage opening around the upper end of the liquidsample intake tube providing a Venturi constriction for producing suction around the upper end of the liquid-sample intake tube whereby to cause the liquid sample to flow upwardly through the liquid-sample intake tube and through the discharge opening thereof.

4. In a spectro-photometric analytical apparatus, a flame generating burner comprising a first tubular member being closed at one end and being open at its other end, a tubular cap disposed upon and extending over the open upper end of said first tubular member, said cap being provided at its upper end with a diametrally reduced substantially circular aperture, a gas inlet means opening into the interior of the first tubular member adjacent to the closed end thereof for introducing a combustible gas thereinto, a second tubular member disposed within, and being of substantially smaller diametral size than the first tubular member and being closed at one end adjacent to the closed end of the first tubular member and terminating at its other end in concentric relation to the aperture for providing in cooperation therewith an annular flame orifice, an inlet tube opening into the second tube for introducing thereinto a flame supporting gas, and a substantially straight liquidsample intake tube extending coaxially through the second tubular member, said liquid-sample intake tube being of substantially capillary dimensions and terminating at one end adjacent to the annular flame orifice so as to discharge sample liquid directly into the flame, said liquidsample intake tube projecting outwardly from the closed end of the second tubular member for insertion into a body of liquid to be analyzed, said second tubular member further being provided at its other end with means having a constricted passage opening around the upper end of the liquid-sample intake tube providing a Ven turi constriction for producing suction around the upper end of the liquid-sample intake tube whereby to cause the liquid sample to flow upwardly through the liquid-sample intake tube and into the flame produced by the burner.

5. In a spectra-photometric analytical apparatus, a flame generating burner comprising a first tubular member being closed at one end and end: of saidfi'rsttubular member, said cap being provided at its upper end with a diametrally re ducedsubstantially circular aperture, saidslipfitted connection being sufficiently tight so that the relative distance between'the'aperture of the "capand the'cl'osed end ofthe first tubular member may be -adjustedto any position within predetermined limits; a gas inlet means opening into ane interior of-the first tubular 'n'iembe'r adjacent the closed end thereof for introducing a com bustibl'e gas thereinto, asecond tubular member disposed within, and being of, substantially smaller diametral" size than the" first tubular member and 'beinglclosed at. one end adjacent to the closed end of the first tubularmember and terminatingat its otherend in-concentric relation to the aperture for providing in cooperation therewith an annular flame ioriifice, an .inletitube opening into the sec-ond tube'adjacent the closed end thereof for introducing thereinto a flame supporting gas, and a substantially straight liquid-sample intake tube extending coaxially through the second tubular member, said liquidsample intake tube being of substantially -cap-- illary dimensions and terminating at one end adjacent to the annular flame orifice so as to discharge sample liquid directly into the flame, said liquid-sample intake tube projecting outwardly from the closed end of the second tubular member for insertion into a body of liquid to be analyzed, said second tubular member further being provided at its other end with means having a constricted passage opening around the upper end of the liquid-sample intake tube providing a Venturi constriction for producing suction around the upper end of the liquid-sample intake tube whereby to cause the liquid sample to flow upwardly through the liquid-sample intake tube and into the flame produced by the burner.

6. In a spectro-photometric analytical apparatus, a flame generating burner comprising a first tubular member being closed at one end and being open at its other end, a tubular cap threadedly fitted upon and extending over the open upper end of said first tubular member, said cap being provided at its upper end with a diametrally reduced substantially circular aperture, said threaded connection being sufiiciently tight so that the relative distance between the aperture of the cap and the closed end of the first tubular member may be adjusted to any position within predetermined limits, a gas inlet means opening into the interior of the first tubular member adjacent the closed end thereof for introducing a combustible gas thereinto, a second tubular member disposed within, and being of substantially smaller diametral size than the first tubular member and being closed at one end adjacent to the closed end of the first tubular member and terminating at its other end in concentric relation to the aperture for providing in cooperation therewith an annular flame orifice, an inlet tube opening into the second tube adjacent the closed end thereof for introducing thereinto a flame supporting gas, and a substantially straight liquid-sample intake tube extending coaxially through the second tubular member, said liquid-sample intake tube being of substantially capillary dimensions and terminating at one end adjacent to the annular flame orifice so as to discharge sample liquid directly into the flame, said liquid-sample intake tube projecting 7 outwardly from the closed end of the second tubular member for insertion into a body of liquid to be analyzed, said second tubular member further being provided at its other end with means having a constricted passage opening around the upper end of the liquid-sample intake tube providing a Venturi constriction for producing suction around the upper end of the liquidsample intake tube whereby to cause the liquid sample to flow upwardly through the liquidsample intake tube and into the flame produced by the burner. THEODORE E. WEICHSELBAUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 932,739 Wiss Aug. 31, 1909 1,252,210 White Jan. 1, 1918 1,536,046 Anthony May 5, 1925 1,561,848 Green Nov. 17, 1925 1,617,166 Schoop Feb. 8, 1927 2,270,442 Jares Jan. 20, 1942 2,532,687 Weichselbaum Dec. 5, 1950 FOREIGN PATENTS Number Country Date 166,264 Germany Dec. 11, 1905 679,452 Germany Aug. 5, 1939 OTHER REFERENCES Cholak et al.: Industrial and Engineering Chemistry, Analytical ed., vol. 16, Dec. 1944, pages 728-734.

Lundegardh: Zeitschrift fur Physik, vol. 66

O of 1930, pages 109-114. 

1. IN A SPECTRO-PHOTOMETRIC ANALYTICAL APPARATUS, A FLAME GENERATING BURNER COMPRISING AN ELONGATED CYLINDRICAL SHELL CHAMBER HAVING AN INLET TUBE ADJACENT ONE END FOR INTRODUCING A COMBUSTIBLE GAS INTO THE CHAMBER, SAID CYLINDRICAL SHELL CHAMBER BEING PROVIDED AT ITS OTHER END WITH A DIAMETRICALLY REDUCED SUBSTANTIALLY CIRCULAR APERTURE, A NOZZLE-TUBE OF SUBSTANTIALLY SMALLER DIAMETER EXTENDING THROUGH SAID CYLINDRICAL SHELL CHAMBER AND HAVING AT ONE END A DISCHARGE NOZZLE ADJACENT TO AND SUBSTANTIALLY CONENCTRICALLY WITHIN AND SPACED FROM THE SUBSTANTIALLY CIRCULAR APERTURE PRODUCING AN ANNULAR FLAME PORT THEREWITH AND BEING PROVIDED WITH A PORTION HAVING A CONSTRICTED PASSAGE OPENING ADAPTED TO CREATE THEREWITH A VENTURI EFFECT, SAID NOZZLE-TUBE BEING PROVIDED ADJACENT ITS OTHER END WITH AN INLET TUBE FOR RECEIVING A HIGH-PRESSURE COMBUSTION-SUPPORTING GAS, AND A LIQUIDSAMPLE INTAKE TUBE OF SMALLER DIAMETER DISPOSED WITHIN AND EXTENDING COAXIALLY THROUGH THE NOZZLE-TUBE, SAID LIQUID-SAMPLE INTAKE TUBE TERMINATING AT ONE END SUBSTANTIALLY CONCENTRICALLY 